Name: 缪缪论坛——缪子物理与缪子技术创新学术论坛
Start: 2026-07-12T08:00:00+08:00
End: 2026-07-13T12:00:00+08:00
Location: Peking University

注册和自由讨论

开幕式和特邀报告

茶歇和自由讨论

学生报告（报告场次和顺序待定）

1

The muon Moon shot: probing the Moon in depth with secondary muons?

Muon tomography has been widely used on Earth to probe internal structures using secondary cosmic-ray muons. We investigate its application to the Moon by studying muons produced in the lunar regolith. Using Monte Carlo simulations, we evaluate the energy spectrum, angular distribution, and flux of muons escaping the lunar surface under different regolith conditions. The results show that the angular muon flux is sensitive to near-surface composition, indicating its potential as a non-invasive tool for lunar subsurface exploration. Possible detector configurations and applications in future lunar missions, including the Chang’e program, are briefly discussed.

Speaker: Mr Zimo Hu (Peking University)
2

Production of lepton-flavor-violating scalars through resonant positive-muon annihilation on atomic electrons

We study a light scalar $\phi$ with lepton-flavor-violating $e$–$\mu$ couplings, directly probed via resonant $\mu^+ e^- \to \phi$ production at high-intensity muon beams. In fixed-target experiments, target electrons are bound and have relativistic momenta, which smear and broaden the resonance. We develop a fully relativistic bound-state framework that accounts for these atomic effects and accurately predicts production rates. Our projections show that HIAF can probe couplings down to $\mathcal{O}(10^{-5})$ with short runs, demonstrating strong sensitivity complementary to traditional LFV searches.

Speaker: Mr Jinhong Shen (Peking University)
3

次级粒子对基于PoCA算法的宇宙射线成像的影响研究

This work reinterprets “noise” in cosmic-ray imaging, showing that PoCA points outside the traditional volume of interest carry valuable physical information. Analysis of four-layer RPC data and Monte Carlo simulations with energy-weighted coordinates confirms that these points arise from muon interactions with materials above the detector, particularly the roof, producing secondary particles. Two main findings emerge: first, in the four-layer system, the first-layer records may come from secondary particles, while the lower three layers reflect true cosmic-ray trajectories; second, the roof strongly influences PoCA point distributions, with roof thickness correlating quantitatively with reconstructed points, measurable via $z$-coordinate analysis. Differences in roofing materials suggest this method could evolve into a novel tomography technique.

Speaker: Mr 荣峰张 (北京大学)
4

Probing Cosmic Ray Composition and Muonphilic Dark Matter via Muon Tomography

This Letter presents a novel cosmic-ray scattering experiment employing a resistive plate chamber muon tomography system. By introducing the scattering angle between incident and outgoing cosmic-ray tracks as a key observable, this approach enables simultaneous studies of secondary cosmic-ray composition and searching for new physics. During a 63-day campaign, 1.18 million cosmic ray scattering events were recorded and analyzed. By performing combined template fits to the observed angular distribution, particle abundances are measured—for example, resolving the electron component at ∼2% precision. Furthermore, constraints are established on elastic muon–dark matter (DM) scattering cross sections for muonphilic dark matter. At the 95% confidence level, the limit reaches 1.61×10−17 cm2 for 1 GeV slow DM, demonstrating the sensitivity limit to light muon-coupled slow DM, in scenarios where a strongly interacting dark matter component is captured and thermalized within Earth, leading to large surface densities.

Speaker: 昊方 (北京大学)
5

正反缪子素转化实验（MACE）研究进展

正反缪子素转化实验（MACE）是我国自主提出的下一代缪子物理实验，旨在寻找破坏带电轻子味的正反缪子素转化过程，是研究超越标准模型的新物理的灵敏探针。该实验将依托我国加速器驱动嬗变研究装置（CiADS）规划的高强度表面缪子束流，预期将转化过程的实验灵敏度较当前国际最好水平提高两个数量级以上。目前已完成概念设计，相关成果发表于《Nuclear Science and Techniques》封面文章。研究系统开展了缪子素产生靶、米歇尔电子磁谱仪、正电子输运系统及正电子探测系统的设计与模拟优化，并评估了新物理探测潜力。实验预期单事例灵敏度可达1.3×10⁻¹³，90%置信度转化概率上限为3.8×10⁻¹³，比国际最佳结果8.3×10⁻¹¹提高两个数量级以上。此外，团队还规划了一期实验，将利用电磁量能器、塑闪定时探测器和塑闪光纤径迹探测器预先研究其他缪子稀有衰变过程，在验证探测器性能的同时进一步拓展物理研究范围。MACE实验是我国缪子物理前沿的重要布局，可与粤港澳大湾区多个缪子源建设计划协同，有望在轻子味破坏研究中取得国际领先成果，为探索超越标准模型的新物理提供关键实验证据。本报告将介绍MACE实验及其近期研究进展。

Speaker: Shihan Zhao (Sun Yat-Sen University)
6

Search for light Dark Sectors with GeV Muon Beams

Sub-GeV light dark matter often requires new light mediators, such as a dark Z' boson in the Lµ − Lτ gauge theory. We study the search potential for such a Z' boson via the process µe −> µeX,with X decaying invisibly, in a muon on-target experiment using a high-intensity 1–10 GeV muon beam from facilities such as HIAF-HIRIBL. Events are identified by the scattered muon and electron from the target using the silicon strip detectors in a single-station telescope system. Backgrounds are suppressed through a trained BDT classifier, and activity in downstream subdetectors remains low. We find that this approach can probe a Z' in the 10 MeV mass range with improved sensitivity. Nearly three orders of magnitude improvement is achievable using a full multi-telescope station system using a 160 GeV muon beam at CERN, such as in the MUonE experiment.

Speaker: Zijian Wang (北京大学)

午餐和讨论

学生报告（报告场次和顺序待定）

7

Progress on Atmospheric Muon Flux Simulation Using CORSIKA

CORSIKA (COsmic Ray SImulations for KAscade) is a widely-used Monte Carlo simulation program for modeling the development of extensive air showers initiated by high-energy cosmic rays in the atmosphere. It tracks the full particle cascade — from the primary cosmic ray interaction down to secondary particles including muons, electrons, and photons — and supports multiple hadronic interaction models such as SIBYLL, QGSJET, and DPMJET.

In this work, we use CORSIKA to simulate the atmospheric muon flux, adopting the Papini parameterization for the primary proton spectrum. Simulated events are processed through a weighted flux extraction pipeline, in which each muon is assigned a Papini weight corresponding to its parent primary energy, and the results are normalized to physical units via an equivalent exposure time derived from the total simulation weight.

For near-vertical muons (zenith angle 0°–5°), the simulated differential energy spectrum shows good agreement with experimental measurements across the energy range of 0.1–10⁵ GeV, validating the simulation framework and normalization procedure.

Current efforts are focused on large zenith angle muons (70°–80°). Preliminary results indicate a systematic discrepancy between the simulated flux and experimental data in this angular regime. The origin of this discrepancy is under investigation, with particular attention to the Earth's curvature effect — which becomes non-negligible for near-horizontal trajectories — and the geometric configuration of the simulation setup.

Speaker: 卓陈 (Peking University)
8

宇宙射线投影偏移粒子流成像技术

宇宙射线μ子成像是一种重要的无损检测技术，但在实际测试时间内实现毫米级分辨率仍面临挑战。为此，我们提出了投影偏移μ子透射成像框架（PμMA），该框架通过融合透射与散射信息，实现了高分辨率成像。与传统依赖散射角定位的方法不同，PμMA通过连接上下游探测器记录的μ子击中位置，构建透射径迹，并将材料引起的μ子散射投影为成像平面内的可观测位置偏移。该方法仅需两个探测器即可实现毫米级分辨率成像，显著提升了可用μ子事例率，并大幅降低了系统成本。我们还发展了多探测器配置方案，通过限制最大散射角，进一步增强了对不同质量厚度材料的鉴别能力。
在模拟研究中，针对30 mm厚铅块，宇宙射线条件下获得的表征分辨能力的刃边宽度最小为1.196 mm；在4 GeV单能平行μ子束条件下，最优刃边宽度可达0.048 mm。在实验验证中，系统在2天内成功实现了对2 mm铜片结构的成像，性能优于同等条件下的传统方法。

Speaker: Zibo Qin (Peking University)
9

缪子散射探测系统探测器位置校正算法研究

在基于宇宙线缪子的散射成像系统中，多层探测器的几何准直精度直接影响径迹重建质量与成像分辨率。针对四层阻性板室（RPC）探测器系统在实际部署中存在的机械平移偏差与面内旋转偏差，本文提出了一种基于径迹直线性约束的全局迭代准直算法。该方法将准直问题分解为平移修正与转角修正两个子问题：平移修正模块通过全局最小二乘直线拟合与残差均值反投影，迭代收敛各层中心偏移量；转角修正模块构建高斯-牛顿非线性优化框架，以留一法残差平方和为目标函数，通过数值差分构造雅可比矩阵并求解阻尼线性方程组，同步更新四层探测器的二维仿射变换矩阵。在准直后，采用留一法计算各层残差分布并以高斯拟合标准差作为空间分辨率指标。该算法不依赖外部精密测量设备，仅利用宇宙线缪子本身的直线性信息即可实现亚毫米级几何标定，为缪子散射成像系统中探测器的离线准直提供了一种通用、可复现的解决方案。

Speaker: Zhe Yang (北京大学物理学院)
10

具有动量测量功能的缪子成像系统的搭建与测试

宇宙线缪子成像技术利用缪子与成像目标的相互作用，通过探测缪子与的径迹变化或计数率变化对客体目标进行成像。传统的缪子成像技术一般不考虑宇宙线缪子本身能量的差异带来的散射性质的影响，在这一前提下需累计一定量的缪子计数才能达到理想的成像效果。模拟表明，如果知道缪子的动量信息，并通过动量数值对缪子的散射角进行加权，就能够通过相对较少的缪子计数实现物质材料鉴别等功能。本文采用飞行时间测量法，基于 MRPC 搭建了一套成像区域面积 $0.25~\mathrm{m^2}$ 的缪子散射成像系统。系统由两个时间分辨 MRPC，4 个位置分辨 MRPC 构成。时间分辨 MRPC 为 4 室 32 气隙结构，宇宙线测试时间分辨率在 $30~\mathrm{ps}$ 左右。位置分辨 MRPC 为 1 室 5 气隙结构，宇宙线测试位置分辨率约为 $0.8~\mathrm{mm}$。时间测量系统电子学采用基于 DRS4 的波形采样板，径迹测量系统电子学采用基于 ADC 的波形采样系统。系统初步对铅砖、铁样件进行了成像扫描，并得出测量结果。

Speaker: Mr 大铭刘 (清华大学)

茶歇和自由讨论

学生报告（报告场次和顺序待定）

晚餐和讨论

缪缪论坛——缪子物理与缪子技术创新学术论坛

School of Physics

Peking University